Hello, I had similar problems with my ZUS charger on my GM OPEL ZAFIRA car.
The cigarette lighter diameter is bigger on these GM OPELs than other cars I used, and it is placed close to the gear shift and hand brake levers. During my rides I often touched the connected phone cable and this caused ZUS to loose contact with the socked - so it restarted phone charge and made annoying beeps and saved the parking location an that was making me mad!
So I made a DIY solution to extend the ZUS charger diameter and now it fits in the lighter socket very secure, No movement, no accidental restarts and power drops.
See the pictures attached. Just cut a few small plastic tabs from a thin plastic ice cream can cover with an appropriate size, wrap them with electric insulation tape and put a small zip tie to hold it to the ZUS charger body.
Not the best looking solution, but works like a charm! In a case I need to use the charger on another car (with smaller lighter socket) - just firmly press the two side metal contacts on ZUS body and slide the zip tie to remove the ‘invention’.
Hope this helps for you.